An ECU (10) is configured to: detect a preceding vehicle (3) ahead of the vehicle (1), and set a speed distribution zone (40) defining a distribution of an allowable upper limit (Vlim) of a relative speed of the vehicle (1) with respect to the preceding vehicle (3) in a region around the preceding vehicle (3); and, execute traveling control of preventing the relative speed of the vehicle (1) with respect to the preceding vehicle (3) from exceeding the allowable upper limit (Vlim) in the speed distribution zone (40), wherein the speed distribution zone (40) includes: an allowable upper limit-zero zone (44) where the allowable upper limit becomes zero; and an entry prohibition zone (42) where entry of the vehicle (1) thereinto is prohibited.